1. Field of the Invention
The present invention relates to a routing information management apparatus and a computer program for managing the routing information (hereinafter, route). Priority is claimed on Japanese Patent Application No. 2007-131535, filed May 17, 2007, the content of which is incorporated herein by reference.
2. Description of Related Art
The Internet is constituted by connecting autonomous TCP (Transmission Control Protocol)/IP (Internet Protocol) networks (autonomous system: AS) provided by various groups (for example, internet service providers (ISP) and companies) to each other. An identification number (AS number) is assigned to each of ASs. AS is constituted from a group of network connection apparatuses (e.g. router) which are operated based on a common routing management policy. The router has a routing table and conducts routing operations of packets based on the routing table. The routing table is constituted from a list of the routing information. The routing information includes: prefixes (combination of an IP address and a bit number of a subnet mask) which are a group of destination addresses; IP addresses of neighboring routers used for reaching the prefix; and the attribute information indicating, for example, a priority. If the routing table includes the routing information which contains a prefix including a certain destination address, it is clear that there is a route to the destination address from the router. The routers update the routing table by exchanging the routing information with each other. BGP (Border Gateway Protocol) is used for exchanging the routing information. The routers have a BGP communication function and exchange the routing information each other. The routing information is called a BMP route update message (UPDATE message). Changing and withdrawing of a route is widely notified by using the UPDATE message. “ANNOUNCE” is a type of the UPDATE message for widely notifying a change of a route. “WITHDRAW” is a type of the UPDAFE message for widely notifying a withdrawal of a route.
In a conventional case, for example, described in Non-Patent Documents 1-5, techniques are known for a network operator of an AS to acquire the routing information obtained by another AS. A conventional technique shown in Non-Patent Document 1 is a mechanism in which one AS provides an input means of router commands to other AS. In accordance with Non-Patent Document 1, a network operator can obtain the latest routing information of other AS by inputting router commands by using “telnet” or via the Web. Non-Patent Documents 2 and 3 show conventional techniques that set the routing information obtained by gathering from multiple AS accessible via Web. The routing information is stored in files in a standard format called “MRT”. MRT is constituted from both RIB (Routing Information Base) which has a snapshot of all prefixes at a predetermined time and UPDATE messages with one-to-one correspondence to all changes of the routes conducted in a predetermined interval. In accordance with the conventional techniques described in Non-Patent Documents 2 and 3, the network operator can refer to the latest and past routing information of other AS by downloading and analyzing files of the routing information. Non-Patent Document 4 and 5 show conventional techniques of a communication program of BGP that receives the routing information by using BGP and stores the routing information in accordance with MRT. However, there are the following problems in the above-described conventional techniques.
In Non-Patent Document 1, it is possible to obtain only the current routing information, and it is not possible to obtain the routing information which can be used for analyzing problems in the past. In Non-Patent Documents 2-5, it takes a long time for obtaining desired routing information by a network operator.
There are two reasons of these problems. A first reason is that both operations of storing information in the MRT format and uploading the information on the Web are conducted at a predetermined interval. A second reason is that the MRT format has been designed without consideration of searching performance of the routing information, and consequently, it takes time to obtain the desired routing information by searching the stored information recorded in the MRT format. For example, the following operations are necessary in order to find a route for reaching an IP address at a specific time. First, RIB just before the specified time is searched, and all routes including the specified IP address are extracted. Regularly, the RIB stores the all routes over the network (in general, 200,000 in the Internet), and it is necessary to search the all routes. In addition, in order to check whether or not there are changes of the routes of the specified IP address, it is necessary to search all the UPDATE messages issued between a time of generating the RIB and a specified time. In addition, in the conventional techniques of Non-Patent Documents 2-5, it is necessary to additionally provide a mechanism for analyzing the routing information. A tool is provided that shows a file which is in the MRT format in text, but a tool is not provided which can analyze the routing information of the specified IP address and/or the specified time that is necessary for investigating problems. Therefore, in conventional cases, the network operator has produced such analysis tools by himself.
[Non-Patent Document 1]
    Internet <URL: http://www.nanog.org/lookingglass.html>, [searched on May 10, 2007][Non-Patent Document 2]    Internet <URL: http://www.routeviews.org/>, [searched on May 10, 2007][Non-Patent Document 3]    Internet <URL: http://www.ripe.net/>, [searched on May 10, 2007][Non-Patent Document 4]    Internet <URL: http://www.quagga.net/>, [searched on May 10, 2007][Non-Patent Document 5]    Internet <URL: http://www.zebra.org/>, [searched on May 10, 2007]